Combine all the umeboshi sauce ingredients (pit the umeboshi plums and chop them up into paste first).
Put all the hanpen burger ingredients into a bowl. Mix and knead well while mashing up the hanpen.
Heat sesame oil in a pan. Form patties with the mixture from Step 2, and brown the patties on each side.
Serve the burgers on a plate with the sauce from Step 1. Garnish with shredded shiso leaves.
For bentos: I made small burgers, brushed them with yakiniku sauce from a bottle, and skewered them.
Note: I used 60 g hanpen from a pack of 2.
Note 2: You could also double the amount and use a 120 g slab of hanpen.
Variation: Divide the burger mix into bite sized portions, and wrap around a square of processed cheese.
Variation, continued: Bake the cheese-wrapped balls in a toaster oven until golden brown. If the cheese is too big it will melt out so be careful. (See the bottom ball...) These are delicious even without sauce.
Story Behind this Recipe
See also Recipe ID: 402073 - "Light and Chewy Hanpen Fritters." I didn't want to admit, but the hanpen was just about at (or even past..) its best-by date. This time, I aimed for a fluffy and light texture rather than a dense chewy texture. You can use any sauce you like or even do without it. The burgers are so easy, I added sauce as a bonus.
Use white or black toasted sesame seeds. You can increase the amount. You just need a little bit of salt and pepper. If you forget to add it, it's not a big deal. If you prefer lighter flavors, not adding salt and pepper might be better. If the onion you're using is watery and 2 teaspoon of katakuriko potato starch flour is not enough, add another teaspoon or add a small packet of bonito flakes. It will be easier to form the burgers.